1. Field of the Invention
The invention relates to an acceleration apparatus comprising an accelerator surrounding an acceleration path with the exception of at least the mouth-side end thereof and an acceleration body which is configured for guided and accelerated motion along the acceleration path and is formed by a missile and preferably a propelling housing at least partially surrounding said missile and in engagement therewith.
2. Description of the Prior Art
Acceleration apparatuses of this type comprise an acceleration path within a usually tubular accelerator and an acceleration body is subjected to an acceleration along said path.
Said acceleration body may directly represent the missile to be accelerated but as a rule forms a propelling housing which surrounds the missile during the entire acceleration.
One accelerator of this known type is formed for instance by a powder gun with a smooth barrel configured for shooting an under-caliber projectile with cartridge-case base.
After the acceleration in the barrel due to the pressure action of the burning powder on the concrete-case base, the parts thereof detach from the actual missile after leaving the barrel muzzle.
This missile may be for example firstly a projectile designed to attack a target or alternatively for example form a flight model which is accelerated in order to be projected with high velocity through the surrounding air; after leaving the mouth observations can be made on the aerodynamic behaviour occurring.
Now, the detaching of the case base or case jacket parts takes place along a certain flight path of the missile in a relatively irregular manner, the parts detached from the missile moving initially substantially along the flight path thereof.
By irregular detaching of the jacket parts the flight path of the missile can be impaired. Furthermore, the degrees of freedom on designing the propelling jacket are restricted because the parts thereof must all detach themselves from the missile simultaneously.
The impairment of the missile by the parasitic aerodynamic forces here is the greater the smaller the density of said missile. Whereas missiles constructed as balanced rods can as a rule settle again after a disturbance, this is possibly not the case with aerodynamic models, missiles of composite fiber material and missiles with cavities.
If a somewhat uniform detachment operation is assumed then this known arrangement suffices fully for instance for a tank gun. If however measurements are to be made on a missile constructed as model, it must also be ensured that jacket parts do not conceal the surface of the missile, cause air streams disturbing the measurements or even strike the measuring devices. These problems can admittedly be handled but they do involve difficulties.
When such an arrangement is used in an aircraft there is also a danger of damage by the parts of the propelling housing flying about in uncontrolled manner.
When using a so-called ram accelerator a missile is fired into a pipe filled with combustible gas.. Between the pipe wall and the missile or projectile said gas is compacted and ignited and it therefore then burns behind the missile, gently but continuously accelerating said missile like a ram jet engine.
Such a ram accelerator is described in German OS 3,808,655.
The mode of operation of such a ram accelerator sets very narrow limits on the outer form of the projectile to be accelerated. Now, if a missile or projectile differs in its shape from the shape required for a ram accelerator from the aerodynamic point of view, then said missile must be surrounded by a suitably shaped propelling housing which after the acceleration has been produced must be removed as rapidly and as interference free as possible from the missile.
Furthermore, hitherto it was also not possible to use such a ram accelerator for after-acceleration of a missile freed from its cartridge-case base because the flight path necessary for reliable detachment of the propelling base parts is too long and because the base parts striking the ram accelerator endanger the operating team.
Another problem involved in the acceleration of models and instrument carriers is that to achieve a necessary final velocity disproportionalPly high acceleration values must be accepted and they are capable of damaging the missile, particularly since in the case of a powder or light-gas gun the acceleration takes place irregularly.
Finally, a problem common to all accelerators is that the exact rotational position with respect to the flight path axis cannot be exactly fixed and therefore there is a possibility of the fired model assuming a flight attitude unsuitable for the measurement to be made.